The prior art is replete with connecting devices for joining two or more wires in electrical contact to splice the same into a given circuit. The devices that are considered relevant to the background of this invention are not the insulation displacement connectors or the wire nut twist-on connectors but connectors where the wires are placed in end-to-end relationship for making a butt splice and maintained in electrical connection by a crimp connector, a weld or similar connection. Often the electrical connections will be insulated using heat-shrinkable tubular components. There are many examples of electrical connection devices which include heat-shrinkable components. Often the heat-shrinkable portion will be in the form of a tube or sleeve. The inner wall of the tube may be coated with an adhesive or sealant. When, positioned within the shrinkable tube, the means for joining conductors is found usually close to the central portion of the heat-shrink sleeve. The joining means is frequently a ring or band of solder as described, for example, in GB 1,149,125; U.S. Pat. No. 4,940,179 and WO 9,007,207. (Other related patents are: U.S. Pat. No. 4,722,471; U.S. Pat. No. 4,300,284; GB 2,020,922; U.S. Pat. No. 4,832,248; WO 8,809,068; U.S. Pat. No. 4,505,421 and U.S. Pat. No. 4,883,924). The use of bands or rings of solder are referred to as solder inserts or preforms. Such inserts perform the conventional function of soldering electrical conductors to provide an electrical connection. In some cases, the solder may be susceptible to and melted by a high frequency alternating currents as described in U.S. Pat. No. 4,987,283 and U.S. Pat. No. 4,852,252. While the solder inserts have a well defined shape, in some cases they may be replaced by an undefined quantity of solder as disclosed in U.S. Pat. No. 4,654,473 and U.S. 4,384,404.
As an alternative, the solder components may be replaced by crimp barrels within the heat-shrink sleeves. Connectors which rely upon crimp barrels are described, for example, in U.S. Pat. No. RE 33591 and U.S. Pat. No. 4,993,149.
Another means of making electrical connection between conductors is revealed in U.S. Pat. No. 5,006,286. In this case the solder is replaced by a conductive gel medium. The gel, located centrally within a heat shrink sleeve, provides a conductive path between conductors which are inserted into and surrounded by, the conductive gel. When heat is applied, the heat-shrink sleeve recovers, gripping the insulation of the conducting wires. This prevents the conductors from withdrawing from the conductive gel. All of the foregoing examples suffer from a common problem. This problem is associated with the positioning of the wire conductors, insulated or otherwise, before they are joined by soldering, crimping or penetration of a conductive gel. This problem is especially acute in the latter case since the wires must be held in the desired relationship until the shrinkage and gripping action of the heat-shrink sleeve is complete. Therefore, to successfully connect conductors, using prior art devices, it is necessary to provide auxiliary clamping means to hold conductors in position, within the connector, prior to soldering, crimping, etc.
One piece of prior art, GB 2,020,922, teaches the use of an additional insert within a heat-shrink sleeve. This insert is used to hold and position wires which are inserted into the heat-shrink sleeve. However, this connecting device is useful only for connecting wires which are inserted from the same end of the connector. Also, it seems that the insert does not effect a gripping action while holding the wires in position nor does it appear useful in providing a reliable electrical connection. Thus, wires inserted and positioned in the connector are not reliably secured and electrically connected until soldering or twisting and heat-shrink procedures have been performed.
The present invention significantly simplifies the process of joining conductors electrically with a solder junction by eliminating the need for auxiliary clamping. It also provides an improvement over crimp connectors which are subject to damage by crimping tools which may cut through the heat-shrinkable insulating layer during the crimping process.